At the moment a hot cake is put in a cooler, the difference between the cakes and the cooler's

temperatures is 50° Celsius. This causes the cake to cool and the temperature difference loses

value every minute.

of its

Write a function that gives the temperature difference in degrees Celsius, D (t), t minutes after the cake

was put in the cooler.

D (t) =

Answer: D (t) = 50 (4/5) ^t

Explanation: If 1/5 of the temperature difference is lost each minute, that means 4/5 of the difference remains each minute. So each minute, the temperature difference is multiplied by a factor of 4/5 (or 0.8).

If we start with the initial temperature difference, 50° Celsius, and keep multiplying by 4/5, this function gives us the temperature difference t minutes after the cake was put in the cooler.

D (t) = 50 (0.8) ^t